Tunisian special forces have killed a senior commander of an Islamic State affiliate during clashes with the group in a central, mountainous region, the Tunisian Ministry of Defense said on Thursday.

Security forces are engaged in a crackdown on Islamic State militants after they carried out four major attacks in the last year. Dozens died in assaults on a Tunis museum, a beach resort and a border town near Libya, crippling Tunisia's vital tourism industry.

Tunisian troops often clash with militants allied with Al Qaeda operating near the Algerian border, but last year's attacks were claimed by fighters loyal to Islamic State or its local affiliate Jund al-Khilafah.

"After monitoring terrorist elements in the Mghila mountains, special forces clashed with the terrorists and killed Saif Eddin Jammali known as Abu Qaqaa, one of the most dangerous terrorist leaders in Tunisia in Jund al-Khilafah," the defence ministry said.

It said the special forces seized weapons and other military equipment in the operation late on Wednesday, without giving more details.

Last week Tunisian forces killed in raids two militants and arrested 37 others, most of them trained in Libya. They had planned sychronized attacks in the capital using explosives and weapons smuggled across from Libya, the authorities said.

Islamic State has carved out a base in Libya, taking over the city of Sirte. Security sources say many of Islamic State in Libya's commanders are Tunisians who have established training camps there and threatened to carry out attacks on Tunisia.